Vaccines are widely and frequently used, particularly in the veterinary and farming industries, with a large number of vaccinations for various diseases, infections and other health related issues available.
In the animal health industry in particular, the use of vaccines to protect against clostridial diseases is widespread.
Adverse effects to the wellbeing of animals may result in decreased yields and therefore sale proceeds (either in terms of the live animal, meat or wool) to the owner. Loss of earnings can be considerable and as such, keeping animals healthy is of prime importance to farmers/animal owners.
Anthelmintic preparations are also widely known and used in the animal health industry for the treatment of helminthiasis. One such anthelmintic is levamisole, the laevorotatory isomer of tetramisole. Levamisole is known to be a particularly effective anthelmintic in ruminant animals when administered at a dosage level of approximately 7.5 mg per kg of animal body weight. Dosages that are too low (less than 6 mg per kg of body weight) are ineffective in treating helminthiasis and can encourage resistance in animals, and high dosages have been shown to have a toxic effect on animals. The combination of a vaccine with levamisole was first disclosed in GB 2030043 (1979). This patent describes an acidic injectable composition for the treatment of helminthiasis and prevention of clostridial diseases in animals, comprising a vaccine in combination with tetramisole or levamisole, with no restrictions claimed on effective dosages.
GB 2050830 (1980) discloses a vaccine in combination with levamisole for the use of improving the response of a ruminant animal to the vaccine. GB 2050830 also discloses that when levamisole is issued in combination with a vaccine, it is preferably administered at a dosage rate of approximately 10 to 17 mg per kg of animal body weight.
Following on from the above patent, Schering Plough has produced and marketed a combination levamisole/vaccine composition for a sheep known as Nilvax™.
Nilvax™ is widely used in the animal health industry and is marketed for the treatment of lambs 20 kilograms and over, through to sheep up to 105 kilograms. Nilvax™ provides a composition containing levamisole and a vaccine, with levamisole present at 6.8% levamisole as the free base (equivalent to 10% levamisole phosphate). The dosage regime recommended for Nilvax™ provides animals with a dose of levamisole base from between 17.5 mg per kg for the lightest animal through to 3.78 mg per kg for a heavier animal of 105 kg.
Using these suggested dosages, the amount of levamisole being administered to the animal varies widely, resulting in potentially toxic levels for the smaller animals and ineffective levels of levamisole for the heavier animals. This variation in dosages can be potentially detrimental to the animals and subsequently may result in stock losses for the farmer. Overdosing on levamisole can result in toxicity to the animal and under dosing can be both ineffective in treating helminthiasis and may also increase the risk that the animal will develop resistance to the drug.
It has also been shown by the inventor that known compositions of vaccine and levamisole do not significantly improve antibody levels within animals for all antigens in a vaccine. In Nilvax™, for example, the amount of levamisole administered in conjunction with the vaccine fluctuates widely depending on the weight of the animal. Therefore, any improvement in vaccine response that can be attributed to the presence of levamisole is not maximized, as a consistent amount of levamisole is not provided to all animals across a weight range when using known dosing regimes and compositions. It is therefore an object of the present invention to provide an improved composition and dosage regime that overcomes the above problems or at least provides the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.